1. Technology Field
The present invention is directed to a data writing method for a rewritable non-volatile memory module, and a memory control circuit unit and a memory storage apparatus using the method.
2. Description of Related Art
Along with the widespread of digital cameras, cell phones, and MP3 in recently years, the consumers' demand for storage media has increased drastically. Since a rewritable non-volatile memory has the characteristics of non-volatility of data, low power consumption, small volume, non-mechanical structure, and fast reading and writing speed, the rewritable non-volatile memory is the most adaptable memory applied in a portable electronic product, e.g., a notebook computer. A solid state drive (SSD) is a storage apparatus which utilizes a flash memory as its storage medium. Therefore, the flash memory industry has become a very popular part of the electronic industry in recent years.
FIG. 1 is a schematic diagram illustrating a flash memory device according to the related art.
Referring to FIG. 1, a flash memory device 1 includes a charge-trapping layer 2 for storing electrons, a control gate 3 for applying a bias voltage, a tunnel oxide layer 4 and an interpoly dielectric layer 5. When data is about to be written to the flash memory device 1, a threshold voltage of the flash memory device 1 may be changed by injecting electrons into the charge-trapping layer 2. Accordingly, a digital level state of the flash memory device 1 is defined to implement a function of storing data. Here, the process of injecting the electrons to the charge-trapping layer 2 is referred to as programming. Otherwise, when the data is about to be removed, the flash memory device 1 is restored to the unprogrammed state by removing the injected electrons from the charge-trapping layer 2.
During operations of writing and erasing, the flash memory device 1 would be worn due to frequently injecting and removing the electrons, which leads to the increased speed of writing the electrons and wider distribution of the threshold voltage. As a result, after being programmed, the storage state of the flash memory device 1 can not be accurately identified, which results in the occurrence of error bits. In particular, in a case that the flash memory device 1 is at a high temperature, the data retention of the flash memory device 1 is decreased, and thereby the occurrence of error bits becomes more serious.
Nothing herein should be construed as an admission of knowledge in the prior art of any portion of the present invention. Furthermore, citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention, or that any reference forms a part of the common general knowledge in the art.